Die casting system and method utilizing high melting temperature materials

ABSTRACT

An example die casting system includes a die comprised of a plurality of die components that define a die cavity configured to receive a molten metal. One of the die components comprises a material that is not reactive with the molten metal and has a melting temperature above 815 degrees Celsius.

BACKGROUND

This disclosure relates generally to casting and, more particularly, toa die casting system for casting high temperature materials.

Die casting involves injecting molten metal directly into a reusable dieto yield a net-shaped component. Die casting has typically been used toproduce components that do not require high thermal mechanicalperformance. For example, die casting is commonly used to producecomponents made from relatively low melting temperature metals, such as,but not limited to: aluminum, zinc, magnesium, and copper. The productsproduced from these alloy systems are not generally subjected to extremeoperating conditions.

Gas turbine engines include multiple components that are subjected toextreme temperatures during operation. For example, the compressorsection and turbine section of the gas turbine engine each includeblades and vanes that are subjected to relatively extreme temperatures,such as temperatures exceeding approximately 1500° F./815° C.

Gas turbine engine components for use in these applications are producedthrough several processes, such as, but not limited to, investmentcasting and forging. Investment casting involves pouring molten metalinto a ceramic shell having a cavity in the shape of the component to becast. Generally, the shape of the component to be produced is derivedfrom a wax pattern or SLA pattern to form the exterior shape of thecomponent. The investment casting process is capital intensive, requiressignificant manual labor, and can be time intensive to produce the finalcomponent. Forging of a component is accomplished through theapplication of localized forces to the desired metal using shapedtooling to plastically deform the metal into the final shape. Whileforging is generally less expensive than investment casting there isstill a significant amount of lead time and capital investment requiredto produce components by this methodology. Wrought product can besubsequently machined into the desired shape, but is less cost effectivefor large volumes of components due to excessive material losses due tomachining.

SUMMARY

An example die casting system includes a die comprised of a plurality ofdie components that define a die cavity, metal delivery system, and partremoval system configured to receive a molten metal. One or more of thedie components comprises a material or materials that are suitable foruse with the molten metal and has a melting temperature above 815degrees Celsius.

An example die casting system includes a die comprised of a plurality ofdie components that define a die cavity configured to receive a moltenmetal, wherein at least one of the plurality of die components comprisesa material selected from a group consisting of a nickel based superalloy, a cobalt based super alloy, an iron-nickel based super alloy, asuitably alloyed iron based alloy, a suitably alloyed copper alloy, anda refractory metal alloy where the refractory metal is either: tungsten,molybdenum, rehenium, niobium, or tantalum.

An example die casting system includes a die comprised of a plurality ofdie components that define a die cavity configured to receive a moltenmetal that has a melting temperature above 815 degrees Celsius. One ofthe die components comprises a ceramic material, or a composite materialsuch as: a metal matrix composite, a ceramic matrix composite, or acombination of independent ceramic and metallic components that comprisethe die components.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example die casting system used to castcomponents.

FIG. 2 illustrates an example component cast with the die casting systemof FIG. 1.

FIG. 3A illustrates the die casting system of FIG. 1 during casting of acomponent.

FIG. 3B illustrates the die casting system of FIG. 1 upon separationfrom a casted component.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, an example die casting system 50 including areusable die 52 having a plurality of die elements 54, 56 that functionto cast a component 55. Although two die elements 54, 56 are depicted inFIG. 1, it should be understood that the die 52 could include more orfewer die elements, as well as other parts and configurations.

The die 52 is assembled by positioning the die elements 54, 56 togetherand holding the die elements 54, 56 at a desired positioning via amechanism 58. The mechanism 58 could include a clamping mechanism ofappropriate hydraulic, pneumatic, electromechanical and/or otherconfigurations. The mechanism 58 also separates the die elements 54, 56subsequent to casting.

The die elements 54, 56 define internal surfaces 62 that cooperate todefine a die cavity 60. A shot tube 64 is in fluid communication withthe die cavity 60 via one or more ports 66 located in the die element54, the die element 56, or both.

A plunger tip and rod 68 are received within the shot tube 64 and ismoveable between a retracted and injection position (in the direction ofarrow A) within the shot tube 64 by a mechanism 80. The mechanism 80could include a hydraulic assembly or other suitable mechanism,including, but not limited to, hydraulic, pneumatic, electromechanical,or any combination thereof.

The shot tube 64 is positioned to receive a molten metal from a meltingunit 82, such as a crucible, for example. The melting unit 82 mayutilize any known technique for melting an ingot of metallic material toprepare a molten metal for delivery to the shot tube 64, including butnot limited to, vacuum induction melting, electron beam melting,induction skull melting, and resistance melting. The molten metal to beused to manufacture the part is melted in the melting unit 82 at alocation that is separate from the shot tube 64 and the die cavity 60.In this example, the melting unit 82 is positioned in close proximity tothe shot tube 64 to reduce the required transfer distance between themolten metal and the shot tube 64.

Example molten metals capable of being used to die cast a component 55include, but are not limited to, nickel based super alloys, titaniumalloys, high temperature aluminum alloys, copper based alloys, ironalloys, molybdenum, tungsten, niobium, or other refractory metals. Thisdisclosure is not limited to the disclosed alloys, and it should beunderstood that any material having a high melting temperature may beutilized to die cast the component 55. As used herein, the term “highmelting temperature” is intended to describe component materials havinga melting temperature of approximately 1500° F./815° C. or higher.

The molten metal is transferred from the melting unit 82 to the shottube 64 in a known manner, such as pouring the molten metal into a pourhole 63 in the shot tube 64, for example. A sufficient amount of moltenmetal is poured into the shot tube 64 to fill the die cavity 60. Theshot tube plunger 68 is actuated to inject the molten metal underpressure from the shot tube 64 into the die cavity 60 to cast thecomponent 55. Although the casting of a single component is depicted,the die casting system 50 could be configured to cast multiplecomponents in a single shot.

The example die casting system 50 depicted in FIG. 1 is illustrativeonly and could include more or less sections, parts and/or components.This disclosure extends to all forms of die casting, including but notlimited to, horizontal or vertical, or inclined die casting systems.

FIGS. 3A and 3B illustrate portions of the die casting system 50 duringcasting (FIG. 3A) and after the die elements 54, 56 separate (FIG. 3B).After the molten metal solidifies within the die cavity 70, the dieelements 54, 56 are disassembled relative to the component 55 by openingthe die 52 via the mechanism 58. In one example, ejector pins 84 areused to move the component 55 from the die cavity 60.

The example die casting system 50 includes portions that are made fromhigh temperature system materials that are able to withstand hightemperatures associated with casting the molten metal into the component55.

In one example, the die elements 54, 56 are made entirely of the hightemperature system material.

In another example, a portion of the die elements 54, 56 are made of thehigh temperature system material. The areas of the cavity 70establishing areas of the component 55 prone to microfractures orthermo-mechanical induced fatigue, such as tight radii areas of the castcomponent, could be made of the high temperature system material. Also,the areas of the die elements 54, 56 establishing the cavity could becoated with the high temperature system material.

In addition to the die elements 54, 56, portions of the shot tube 64,the shot tube plunger 68, or the ejector pins 84 include the hightemperature system material in some examples.

Notably, the example high temperature system material does notreactively interact with the molten material. That is, there is nosubstantial chemical reaction, melting, welding, soldering, or alloyingbetween the high temperature system material and the molten material.

Many techniques could be used to incorporate the high temperature systemmaterial into the die casting system 50. For example, the die elements54, 56 could incorporate the high temperature system material bycasting, machining, slip casting, injection molding, isostatic pressing(hot or cold), sintering, stamping, forging, direct metal lasersintering etc.

Example materials that could be used as the high temperature systemmaterial include metallic materials, such as a nickel based super alloy,a cobalt based super alloy, a iron-nickel based super alloy, a suitablyalloyed iron based alloy, a suitably alloyed copper alloy, or arefractory metal (tungsten, molybdenum, rehenium, niobium, or tantalum)based alloy. These materials can be manufactured into suitable dieblocks using a variety or processing techniques including, but notlimited to: cold forging, hot forging, conventional casting, directionalsolidified casings with or without orientation control, extrusions, orhot isostatic compaction of powder metallurgy products. Example nickelbased super alloys include: IN100, IN713C, IN792 forged; Firstgeneration nickel base single crystal alloys (0% Rhenium) such as U.S.Pat. No. 4,209,348, U.S. Pat. No. 4,597,809; Second generation nickelbase single crystal alloys (3% Rhenium) such as U.S. Pat. No. 4,719,080;Third generation nickel base single crystal alloys (6% Rhenium) such asU.S. Pat. No. 5,366,695; Fourth generation nickel base single crystalalloys (6% Rhenium, 3% Ruthenium) such as U.S. Pat. No. 6,007,645; Fifthgeneration nickel base nickel base single crystal alloys (6+% Rhenium,6+% Ruthenium) such as TMS-173; Directionally solidified firstgeneration (0% Rhenium) columnar structure alloys such as U.S. Pat. No.3,785,809; and second generation (3% Rhenium) columnar structure alloyssuch as U.S. Pat. No. 5,068,084. Example nickel-iron super alloysinclude Invar 909, IN718. Example alloyed based iron alloys include:H23, H42, M35, M36, M42, M46, M62 and Greek Ascoloy. Example cobalt castalloys include Mar-M-509, and Stellite 31. Example refractory metalalloys include: Anvilloy 1150, TZM (tungsten-molybdenum-zirconium),molybdenum-rhenium systems, tantalum −10% tungsten, and tungsten-rheniumsystems.

Example materials that can be used as the high temperature systemmaterial include ceramic materials, such as boron nitride, siliconnitride, silicon aluminum oxy nitride (SiAlON), aluminum nitride,aluminum oxide, silicon carbide, titanium carbide, tungsten carbide,zirconium oxide, boron carbide, titanium diboride, niobium boride,zirconium boride, hafnium diboride, niobium carbide, zirconium carbide,hafnium carbide, graphite etc.

Example materials that can be used as the high temperature systemmaterial include metal matrix composite materials, such ascopper-tungsten, copper-molybdenum, copper-molybdenumcopper-copper,copper-niobium, Silvar, aluminium silicon carbide.

Example materials that can be used as the high temperature systemmaterial include ceramic matrix composite materials, such as C—SiC,SiC—SiC, SiC—Si₃N₄, C—ZrC, C—HfC, C—SiC—ZrC, C—SiC—HfC, C—TaC andC—TaC—HfC.

The example component 55 is casted using the example die casting system50 described above. In this example, the die casted component 55 is ablade for the gas turbine engine (not shown), such as a turbine bladefor a turbine section of the gas turbine engine. However, thisdisclosure is not limited to the casting of blades. For example, theexample die casting system 50 of this disclosure may be utilized to castaeronautical components including blades, vanes, combustor panels, bladeouter air seals, or any other component subjected to extremeenvironments, including non-aeronautical components.

The example component 55 includes tightly radiused areas 86 that aremore susceptible to thermo mechanical fatigue that other areas of thecomponent 55. The areas of the die elements 54, 56 that interface withthe areas 86 include a layer of high temperature system material, forexample.

Features of the disclosed examples include a die casting system thatincludes system materials that are have a relatively high melt point andthat are non-reactive with a component material. The system materialsfacilitate die casting of components that are made from componentmaterials having a high melt point. The system materials reducethermo-mechanical fatigue in the cast component. The system materialsare effective for moving thermal energy away from the cast component.The system materials absorb the heat input from molten metals.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this disclosure. Thus, the scope of legal protectiongiven to this disclosure can only be determined by studying thefollowing claims.

1. A die casting system, comprising: a die comprised of a plurality ofdie components that define a die cavity configured to receive a moltenmetal, wherein at least one of the plurality of die components comprisesa material that is not reactive with the molten metal and has a meltingtemperature above 815 degrees Celsius.
 2. The die casting system ofclaim 1, comprising a shot tube in fluid communication with said diecavity, a shot tube plunger moveable within said shot tube tocommunicate the molten metal into said die cavity, wherein at least oneof the shot tube and the shot tube plunger comprises the material. 3.The die casting system of claim 2, wherein a tip of the shot tubeplunger comprises the material.
 4. The die casting system of claim 1,comprising at least one ejector pin configured to be moved relative tothe die cavity, wherein the at least one ejector pin comprises thematerial.
 5. A die casting system, comprising: a die comprised of aplurality of die components that define a die cavity configured toreceive a molten metal, wherein at least one of the plurality of diecomponents comprises a material selected from a group consisting of anickel based super alloy, a cobalt based super alloy, an iron-nickelbased super alloy, a suitably alloyed iron based alloy, a suitablyalloyed copper alloy, and a refractory metal based alloy.
 6. The diecasting system of claim 5, comprising a shot tube in fluid communicationwith said die cavity and a shot tube plunger moveable within said shottube to communicate the molten metal into said die cavity, wherein atleast one of the shot tube and the shot tube plunger comprises thematerial.
 7. The die casting system of claim 6, wherein a tip of theshot tube plunger comprises the material.
 8. The die casting system ofclaim 5, comprising at least one ejector pin configured to be movedrelative to the die cavity, wherein the ejector pin comprises thematerial.
 9. The die casting system of claim 5, wherein the at least oneof the plurality of die components comprises a die.
 10. The die castingsystem of claim 5, wherein another of the plurality of die componentscomprises a material that is not in the group.
 11. The die castingsystem of claim 5, wherein the refractory metal comprises a materialselected from a group consisting of tungsten, molybdenum, rehenium,niobium, and tantalum.
 12. A die casting system, comprising: a diecomprised of a plurality of die components that define a die cavityconfigured to receive a molten metal that has a melting temperatureabove 815 degrees Celsius, wherein at least one of the plurality of diecomponents comprises a material that is a ceramic material, a metalmatrix composite material, a ceramic matrix composite material, or somecombination of these.
 13. The die casting system of claim 12, comprisinga shot tube in fluid communication with said die cavity and a shot tubeplunger moveable within said shot tube to communicate the molten metalinto said die cavity, wherein at least one of the shot tube and the shottube plunger comprises the material.
 14. The die casting system of claim13, wherein the leading contact surface of the plunger tip or the entireplunger comprises the material.
 15. The die casting system of claim 12,wherein the material comprises a material selected from a groupconsisting of boron nitride, silicon nitride, silicon aluminum oxynitride (SiAlON), aluminum nitride, aluminum oxide, silicon carbide,titanium carbide, tungsten carbide, zirconium oxide, boron carbide,titanium diboride, niobium boride, zirconium boride, hafnium diboride,niobium carbide, zirconium carbide, hafnium carbide, and graphite. 16.The die casting system of claim 15, comprising a shot tube in fluidcommunication with said die cavity and a shot tube plunger moveablewithin said shot tube to communicate the molten metal into said diecavity, wherein at least one of the die components and the shot tubeplunger comprises the material.
 17. The die casting system of claim 15,comprising at least one ejector pin configured to be moved relative tothe die cavity, wherein the ejector pin comprises the material.
 18. Thedie casting system of claim 12, wherein the metal matrix compositematerial comprises a material selected from a group consisting ofcopper-tungsten, copper-molybdenum, copper-molybdenumcopper-copper,copper-niobium, Silvar, aluminium silicon carbide.
 19. The die castingsystem of claim 12, wherein the ceramic material comprises a materialselected from a group consisting of C—SiC, SiC—SiC, SiC—Si₃N₄, C—ZrC,C—HfC, C—SiC—ZrC, C—SiC—HfC, C—TaC and C—TaC—HfC.